Magnetic earth bit seal

ABSTRACT

An earth bit seal includes a magnetic ring that determines how strongly the earth bit seal engages a lug and/or cone of an earth bit. The earth bit seal also includes a flexible ring positioned away from any dynamic sealing surfaces that engage the lug or cone. The flexible ring is positioned away from the dynamic sealing surfaces so that, if it becomes impregnated with debris, it will not act as an abrasive ring that undesirably removes material from them, or from the lug and cone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 60/869,494 filed on Dec. 11, 2006, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a seal assembly for earth bits.

2. Description of the Related Art

An earth bit is commonly used to bore holes into earthen annulus. Such holes may be bored for many different reasons, such as drilling for oil, minerals and geothermal steam. There are several different types of earth bits that are used for drilling. One type is a rotary earth bit and, in a typical setup, it includes three earth bit cutting cones rotatably mounted to a corresponding lug. The lugs are mounted on an earth bit body and, as the earth bit body is rotated in the bore hole, the earth bit cutting cones rotate in response to contacting the earthen annulus.

In normal use, the earth bit contacts hard rock formations while being exposed to extreme conditions, such as high temperatures and pressures. As a result, the earth bit tends to wear down. The lugs are especially prone to wearing down because of friction between them and the cutting cones. Earth bit seals are often used to reduce the friction by retaining a lubricant between the lugs and cutting cones and by keeping debris away. Reducing friction between the lugs and cutting cones increases the lifetime of the earth bit.

The earth bit seals are generally in rotating contact with the lug and/or cutting cone. The surface portion of the earth bit seal in rotating contact with the lug or cutting cone is typically known as a dynamic sealing surface, and the surface portion of the earth bit seal in static contact with the earth bit lug or cutting cone is typically known as a static sealing surface.

Earth bit seals are often manufactured from elastomeric materials and generally experience the extreme conditions mentioned above. The elastomeric material can become impregnated with debris, especially if it forms a part of the dynamic sealing surface. An elastomeric material impregnated with debris is more likely to tear. Further, an elastomeric material impregnated with debris acts as an abrasive ring that undesirably removes material from the earth bit seal, lug and cutting cone.

To reduce the amount of material removed, many earth bit seals include metal face seals which form the dynamic sealing surface. This is because metal face seals do not become impregnated with debris as easily as seals made with elastomeric materials. The metal face seal generally contacts a metal surface of either the cutting cone or lug, or another metal face seal. However, it is often desirable to engage, with a larger force, the dynamic sealing surface of the metal face seal with the surface of the cutting cone or lug to provide a stronger seal between them.

BRIEF SUMMARY OF THE INVENTION

The present invention employs an earth bit seal assembly, which is used to provide a seal between a lug and cutting cone of an earth bit. The earth bit seal assembly includes first and second rigid rings coupled together with a flexible ring. In accordance with the invention, the flexible ring is spaced from the lug and cutting cone to reduce the likelihood of it becoming impregnated with debris and wearing down. In some embodiments, the flexible ring does not form a dynamic seal with the lug or cutting cone.

Further, in accordance with the invention, the flexible ring allows the first and second rigid rings to move relative to each other. For example, the flexible ring allows the first and second rigid rings to move towards and away from each other. The flexible ring allows the first rigid ring to move towards and away from the lug and the flexible ring allows the second rigid ring to move towards and away from the cutting cone. The flexible ring allows the first and second rigid rings to move relative to each other so that the seal provided by the earth bit seal assembly is less likely to break in response to movement of the cutting cone and lug relative to each other.

In some embodiments, the earth bit seal assembly includes a first magnetic ring carried by the first rigid ring, wherein the flexible ring allows the first magnetic ring to move relative to the second rigid ring. For example, the flexible ring allows the first magnetic ring to move towards and away from the second rigid ring.

In some embodiments, the earth bit seal assembly includes a second magnetic ring carried by the second rigid ring, wherein the flexible ring allows the second magnetic ring to move relative to the first rigid ring. For example, the flexible ring allows the second magnetic ring to move towards and away from the first rigid ring.

The first magnetic ring couples the first rigid ring to the lug and the second magnetic ring couples the second rigid ring to the cutting cone. The first magnetic ring couples the first rigid ring to the lug so that the seal therebetween is less likely to be broken in response to movement of the cutting cone relative to the lug. Further, the second magnetic ring couples the second rigid ring to the cutting cone so that the seal therebetween is less likely to be broken in response to movement of the cutting cone relative to the lug.

Further features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an earth bit having an earth bit seal assembly, in accordance with the invention.

FIG. 2 a is a view of an earth bit seal assembly which can be used with the earth bit of FIG. 1, in accordance with the invention.

FIG. 2 b is an exploded perspective view of the earth bit seal assembly of FIG. 2 a.

FIG. 2 c is a side view of the earth bit seal assembly of FIG. 2 a in the unflexed condition.

FIGS. 2 d and 2 e are side views of the earth bit seal assembly of FIG. 2 a in the flexed condition.

FIG. 3 a is a side view of an earth bit seal assembly 105 b which can be used with the earth bit of FIG. 1, in accordance with the invention.

FIG. 3 b is an exploded perspective view of the earth bit seal assembly of FIG. 3 a.

FIGS. 3 c and 3 d are side views of the earth bit seal assembly of FIG. 3 a in unflexed and flexed conditions, respectively.

FIG. 4 a is a side view of an earth bit seal assembly which can be used with the earth bit of FIG. 1, in accordance with the invention.

FIG. 4 b is an exploded view of the earth bit seal assembly of FIG. 4 a.

FIG. 4 c is a side view of the earth bit seal assembly of FIG. 4 a in the unflexed condition.

FIGS. 4 d and 4 e are side views of the earth bit seal assembly of FIG. 4 a in the flexed condition.

FIGS. 5 a and 5 b are perspective and bottom views, respectively, of a magnetic ring, which can be included with the earth bit seal assemblies of FIGS. 1, 2 a, 3 a and 4 a.

FIG. 5 c is a bottom view of another embodiment of a magnetic ring, which can be included with the earth bit seal assemblies of FIGS. 1, 2 a, 3 a and 4 a.

FIGS. 6 a and 6 b are flow diagrams of methods of providing a seal for an earth bit, in accordance with the invention.

FIG. 6 c is a flow diagram of a method of manufacturing an earth bit seal assembly, in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a cross-sectional view of an earth bit 100, in accordance with the invention. In this embodiment, earth bit 100 includes a lug 101 and cutting cone 102, wherein cutting cone 102 is rotatably coupled to and retained by lug 101. Cutting cone 102 can be rotatably coupled to lug 101 in many different ways. In this embodiment, cutting cone 102 is rotatably coupled to lug 101 with roller bearings 106 and 107, as well as with ball bearings 108. Cutting cone 102 can be retained by lug 101 in many different ways, such as with the use of ball bearings 108.

The rotation of cutting cone 102 about lug 101 is facilitated by retaining a lubricant in a region 110 between them. The lubricant reduces the friction between lug 101 and cutting cone 102 and lubricates roller bearings 106 and 107 and ball bearings 108. The rotation of cutting cone 102 about lug 101 is also facilitated by restricting the flow of debris into region 110. Earth bit 100 includes several debris entry regions, two of which are denoted as regions 103 and 104. Regions 103 and 104 extend from a region 109 external to earth bit 100 to region 110 between lug 101 and cone 102. The flow of debris through regions 103 and 104 and into region 110 can undesirably increase the friction between lug 101 and cutting cone 102. Further, the flow of lubricant through regions 103 and 104 and out of region 110 can undesirably increase the friction between lug 101 and cutting cone 102.

In this embodiment, earth bit 100 includes an earth bit seal assembly 105 positioned so it extends through regions 103 and 103 and forms a seal between lug 101 and cutting cone 102. Seal assembly 105 is positioned to retain lubricant in region 110 and to restrict the flow of debris into region 110.

In accordance with the invention, earth bit seal assembly 105 includes two rigid rings coupled together with a flexible ring, wherein the flexible ring does not form a dynamic seal with lug 101 or cutting cone 102. Further, in accordance with the invention, the flexible ring allows the first and second rigid rings to move relative to each other. In this way, seal assembly 105 is repeatably moveable between flexed and unflexed conditions. For example, the flexible ring allows the first and second rigid rings to move towards and away from each other. The flexible ring allows the first rigid ring to move towards and away from lug 101 and allows the second rigid ring to move towards and away from cutting cone 102. In this way, earth bit seal 105 is less likely to break the seal between cutting cone 102 and lug 101 in response to movement of cutting cone 102 relative to lug 101.

It should be noted that, in some situations, a portion of earth bit seal assembly 105 can be in the flexed condition and another portion can be in the unflexed condition. For example, the portion of seal assembly 105 in region 103 can be in the flexed condition and the portion of seal assembly 105 in region 104 can be in the unflexed condition. Further, the portion of seal assembly 105 in region 104 can be in the flexed condition and the portion of seal assembly 105 in region 103 can be in the unflexed condition. In general, the portions of seal assembly 105 in the flexed and unflexed conditions depends on the relative movement between lug 101 and cutting cone 102.

It should also be noted that the portion of the flexible ring in region 103 is stretched when seal assembly 105 in region 103 is in the flexed condition. Further, the portion of the flexible ring in region 104 is stretched when seal assembly 105 in region 104 is in the flexed condition. The portion of the flexible ring in region 103 is unstretched when seal assembly 105 in region 103 is in the unflexed condition. The portion of the flexible ring in region 104 is unstretched when seal assembly 105 in region 104 is in the unflexed condition. In the unstretched condition, portions of the flexible ring can be compressed or uncompressed. In general, the compression and uncompression of the flexible ring depends on the relative movement between lug 101 and cutting cone 102.

In accordance with the invention, earth bit 100 further includes a first magnetic ring which couples the first rigid ring to lug 101, wherein the flexible ring allows the first magnetic ring to move relative to the second rigid ring. For example, the flexible ring allows the first magnetic ring to move towards and away from the second rigid ring. The first magnetic ring couples the first rigid ring to lug 101 so that the seal therebetween is less likely to be broken in response to relative movement between lug 101 and cutting cone 102.

In some embodiments, earth bit 100 includes a second magnetic ring which couples the second rigid ring to cutting cone 102, wherein the flexible ring allows the second magnetic ring to move relative to the first rigid ring. For example, the flexible ring allows the second magnetic ring to move towards and away from the first rigid ring. The second magnetic ring couples the second rigid ring to cutting cone 102 so that the seal therebetween is less likely to be broken in response to relative movement between lug 101 and cutting cone 102.

In accordance with the invention, the first and second magnetic rings determine the force with which seal assembly 105 engages lug 101 and/or cone 102. A stronger seal is provided by seal assembly 105 between lug 101 and cone 102 if the force with which seal assembly 105 engages them increases. Further, a weaker seal is provided by seal assembly 105 between lug 101 and cone 102 if the force with which seal assembly 105 engages them decreases. If seal assembly 105 provides a stronger seal between lug 101 and cone 102, less material can flow between regions 109 and 110. If seal assembly 105 provides a weaker seal between lug 101 and cone 102, more material can flow between regions 109 and 110.

In this embodiment, the flexible ring restricts the flow of lubricant and debris between regions 109 and 110. In accordance with the invention, the flexible ring is positioned away from the dynamic sealing surfaces of seal assembly 105. The flexible ring is positioned away from the dynamic sealing surfaces so that it is less likely to become impregnated with debris. The flexible ring is positioned away from the dynamic sealing surfaces so that, if it becomes impregnated with debris, it will not act as an abrasive ring that removes material from lug 101 and cone 102. If material is undesirably removed from lug 101 and cone 102, the static and dynamic surfaces of seal assembly 105 may not be able to sealingly engage them. If the static and dynamic surfaces of seal assembly 105 cannot sealingly engage lug 101 and cone 102, material is more likely to undesirably flow between regions 109 and 110. The material typically flows through the interfaces between seal assembly 105 and lug 101 and cone 102.

It should be noted that the earth bit seals described herein can be used in an axial or radial sealing configuration. An axial sealing configuration includes upper and lower rigid rings while a radial sealing configuration includes inner and outer rigid rings. However, only an axial sealing configuration is shown in the drawings.

FIG. 2 a is a view of an earth bit seal assembly 105 a in region 104, in accordance with the invention, which replaces seal assembly 105 of FIG. 1. Seal assembly 105 a forms a dynamic sealing surface 112 with lug 101. Further, seal assembly 105 a forms static sealing surfaces 111 a and 111 b with cutting cone 102. In this embodiment, seal assembly 105 a includes rigid rings 120 and 121 coupled together with a flexible ring 122, which extends between them. Flexible ring 122 and rigid rings 120 and 121 restrict the flow of material between regions 109 and 110. Hence, flexible ring 122 and rigid rings 120 and 121 block debris from entering region 110 and keeps the lubricant in region 110 from flowing to region 109. In accordance with the invention, earth bit seal assembly 105 a is repeatably moveable between flexed and unflexed conditions, as will be discussed in more detail with FIGS. 2 c, 2 d and 2 e.

In this embodiment, seal assembly 105 a is carried by cutting cone 102 so that it rotates therewith. Flexible ring 122 is engaged with rigid ring 121 so that they do not rotate relative to each other. Flexible ring 122 engages cutting cone 102 and forms static sealing surface 111 a and rigid ring 120 engages lug 101 and forms a portion of dynamic sealing surface 112. Another portion of dynamic sealing surface 112 is formed by magnetic rings 115 and 116. It should be noted that rigid ring 120 also forms static sealing surface 111 b with cutting cone 102. It should also be noted that in other embodiments, seal assembly 105 a can be carried by lug 101 and have a dynamic sealing surface engaged with cone 102 and a static sealing surface engaged with lug 101.

In accordance with the invention, flexible ring 122 does not form a dynamic seal with lug 101 or cutting cone 102, so that it is less likely to become impregnated with debris and wear down. Hence, flexible ring 122 does not form a portion of dynamic sealing surface 112. Instead, flexible ring 122 is spaced from dynamic sealing surface 112 by rigid ring 120.

FIG. 2 b is an exploded perspective view of earth bit seal assembly 105 a. Flexible ring 122 can have many different configurations, but, in this embodiment, it is annular in shape and includes a groove 124, wherein groove 124 is downwardly facing and sized and shaped to receive rigid ring 121. Flexible ring 122 includes a tongue 123 which extends along its outer diameter and is sized and shaped to be received by rigid ring 120. Tongue 123 extends outwardly and groove 124 extends downwardly so that they extend at a non-zero angle relative to each other.

Rigid rings 120 and 121 can have many different configurations, but, in this embodiment, rigid ring 121 has a rectangular cross-section and is sized and shaped to be received by groove 124. Further, rigid ring 120 includes a groove 125 extending along its inner diameter, wherein groove 125 is sized and shaped to receive tongue 123.

In this embodiment, rigid ring 120 includes a downwardly facing groove 126 sized and shaped to receive a magnetic ring 115. It should be noted that, in some embodiments, rigid ring 120 can include a groove sized and shaped to receive a magnetic ring 116. However, in this embodiment, magnetic ring 116 engages a sidewall of rigid ring 120. Magnetic rings 115 and 116 are attached to rigid ring 120 and magnetically couple it to lug 101, as shown in FIG. 2 a.

In some embodiments, magnetic rings 115 and 116 are replaced with an L-shaped magnetic ring 117. Magnetic ring 117 is L-shaped because it has an L-shaped cross-section. In these embodiments, L-shaped magnetic ring 117 includes a portion 115 a which extends through groove 126 and another portion 116 a which extends along the sidewall of rigid ring 120. Magnetic ring 117 is attached to rigid ring 120 and magnetically couples it to lug 101 in a manner the same or similar to magnetic rings 115 and 116. It should be noted that flexible ring 122 and rigid rings 120 and 121, as well as magnetic rings 115, 116 and 117, are annular members as will be discussed in more detail with FIGS. 5 a, 5 b and 5 c.

The rings included in earth bit seal assembly 105 can be coupled together in many different ways. Here, flexible ring 122 is coupled to rigid rings 120 and 121 using an adhesive material. However, in other examples, flexible ring 122 can be coupled to rigid rings 120 and 121 using mechanical, chemical or thermal methods. These methods often include compression, bonding, and/or vulcanization. Magnetic rings 115, 116 and 117 can be coupled to a rigid ring using the same or similar methods.

The flexible ring and rigid rings can include many different types of materials. However, the material included in the rigid rings is more rigid than the material included in the flexible ring. Flexible ring 122 can include materials, such as an elastomer, vulcanite, polyurethane, Teflon, etc. These materials can be formed in many different ways, such as machining, injection molding, compression molding or a similar process. Rigid rings 120 and 121 can include metal materials, such as steel. Magnetic rings 115, 116 and 117 can include many different types of magnetic materials, such as rare earth elements.

Magnetic ring 115 is carried by rigid ring 120 so it is positioned adjacent to dynamic sealing surface 112 a. In this way, magnetic ring 115 and rigid ring 120 form portions of dynamic sealing surface 112 a. Magnetic ring 115 is magnetically attracted to the material included in lug 101. Hence, the strength of the seal provided by seal assembly 105 a depends on the magnetic attraction of magnetic ring 115 to lug 101. In the embodiment in which seal assembly 105 a is carried by lug 101 and dynamic sealing surface 112 engages cone 102, seal assembly 105 a is rearranged so that the strength of its seal depends on the magnetic attraction of magnetic ring 115 to cutting cone 102.

An advantage of seal assembly 105 a is that rigid ring 120 is “energized” into a dynamic sealing situation with lug 101 by the magnetic attraction of magnetic ring 115 to lug 101. In this embodiment, flexible ring 122 energizes rigid ring 120 into a dynamic sealing situation with lug 101 to a lesser extent, but this is mostly accomplished by magnetic ring 115. Hence, magnetic ring 115 affects how strongly dynamic sealing surface 112 engages lug 101 and this determines how much material can flow through the interface between lug 101 and seal assembly 105 a.

Another advantage of seal assembly 105 a is that flexible ring 122 is spaced apart from dynamic sealing surfaces 112 a and 112 b by magnetic ring 115 and rigid ring 120. Hence, flexible ring 122 is less likely to become impregnated with debris, which can cause the abrasion of surfaces 112 a and 112 b and/or the surface of lug 101 that engages seal assembly 105 a. The abrasion of surfaces 112 a and 112 b and lug 101 involves the removal of material therefrom and weakens the seal between lug 101 and cone 102 provided by seal assembly 105 a. This allows more material to undesirably flow between regions 109 and 110, as discussed above. Flexible ring 122 allows rigid rings 120 and 121 to move relative to each other to account for movement of lug 101 and cutting cone 102 relative to each other. Hence, the strength of the seal provided by seal assembly 105 a remains strong even as lug 101 and cutting cone 102 rotate.

It should be noted that seal assembly 105 a generally includes one or more magnetic rings. For example, seal assembly 105 a can include magnetic ring 115 or magnetic rings 115 and 116 to provide a stronger seal. It should also be noted that magnetic rings 115 and 116 can have many different configurations. Here, they are each shown as including a single magnetic ring for illustrative purposes. However, they can be magnetic rings having separate magnetic elements carried by a base ring, as discussed in more detail with FIG. 5 c.

In this embodiment, magnetic ring 116 is oriented at a non-zero angle relative to magnetic ring 115, wherein the non-zero angle is ninety degrees. However, the non-zero angle can have other values in other embodiments. In some embodiments, rigid ring 120 can carry one magnetic ring and rigid ring 121 can carry another, as will be discussed in more detail with FIGS. 3 a and 3 b.

FIGS. 2 c and 2 d are side views of earth bit seal assembly 105 a in unflexed and flexed conditions, respectively. In accordance with the invention, earth bit seal assembly 105 a is repeatably moveable between the flexed and unflexed conditions. Earth bit seal assembly 105 a can be moved between the flexed and unflexed conditions in many different ways. One way seal assembly 105 a is moved between the flexed and unflexed conditions is in response to the movement between lug 101 and cutting cone 102. For example, cutting cone 102 can move in a radial direction, as indicated by a direction arrow 127, and a non-radial direction, as indicated by a direction arrow 128. Movement of cutting cone 102 in non-radial direction 128 is in response to a force which moves cutting cone 102 towards and away from lug 101. Further, movement of cutting cone 102 in radial direction 127 is in response to a force which moves cutting cone 102 along lug 101. These forces are generally provided in response to cutting cone 102 engaging earthen annulus.

It should be noted that flexible ring 122 bends in response to force applied in direction 128, as shown in FIG. 2 e. Hence, earth bit seal assembly 105 a is moved between the flexed and unflexed conditions by stretching and bending flexible ring 122. When flexible ring 122 is not stretched or bent, earth bit seal assembly 105 a is in the unflexed condition. When flexible ring 122 is stretched and/or bent, earth bit seal assembly 105 a is in the flexed condition.

Earth bit seal assembly 105 moves between the flexed and unflexed conditions in response to the relative movement between cutting cone 102 and lug 101 for many different reasons. One reason is that flexible ring 122 is coupled to cutting cone 102 and rigid ring 120 is magnetically coupled to lug 101 with magnetic rings 115 and 116. Further, flexible ring 122 and rigid ring 120 are coupled together, as discussed in more detail above. Hence, movement of cutting cone 102 relative to lug 101 stretches and compresses flexible ring 122.

FIG. 3 a is a side view of an earth bit seal assembly 105 b in region 103, in accordance with the invention, which replaces seal assembly 105 of FIG. 1. Seal assembly 105 b forms dynamic sealing surfaces 112 a and 112 b with cutting cone 102 and lug 101, respectively. In this embodiment, seal assembly 105 b includes rigid rings 130 and 131 coupled together with a flexible ring 132, which extends between them. Flexible ring 132 restricts the flow of material between rigid rings 130 and 131. Flexible ring 132 and rigid rings 130 and 131 block debris from entering region 110 and keeps the lubricant in region 110 from flowing to region 109. In accordance with the invention, earth bit seal assembly 105 b is repeatably moveable between flexed and unflexed conditions, as will be discussed in more detail with FIGS. 3 c and 3 d.

FIG. 3 b is an exploded perspective view of earth bit seal assembly 105 b. Flexible ring 132 can have many different configurations. In this embodiment, flexible ring 132 is annular and includes portions 132 a and 132 b which are oriented at a non-zero angle relative to each other.

Rigid rings 130 and 131 can have many different configurations. In this embodiment, rigid ring 130 includes a groove 133 which extends along its inner periphery and an upwardly facing groove 134. Groove 133 is oriented at a non-zero angle relative to groove 134. Groove 133 is sized and shaped to receive portion 132 a of flexible ring 132. Further, groove 134 is sized and shaped to receive magnetic ring 115.

In this embodiment, rigid ring 131 includes a downwardly facing groove 136 sized and shaped to receive magnetic ring 116. Rigid ring 131 includes a groove 135 which faces outwardly and upwardly and is sized and shaped to receive portion 132 b of flexible ring 132. The rings in earth bit seal assembly 105 b can be coupled together in many different ways, such those discussed above with seal assembly 105 a. Further, it should also be noted that the rings included in earth bit seal assembly 105 b can include many different materials, such as those discussed above with seal assembly 105 a.

As best seen in FIG. 3 a, magnetic ring 115 is carried by rigid ring 130 so that rigid ring 130 is magnetically coupled with cutting cone 102. Rigid ring 130 and magnetic ring 115 form dynamic sealing surface 112 a, which is engaged with cutting cone 102. Further, magnetic ring 116 is carried by rigid ring 131 so that rigid ring 131 is magnetically coupled with lug 101. Rigid ring 131 and magnetic ring 116 form dynamic sealing surface 112 b, which is engaged with lug 101.

Magnetic rings 115 and 116 are magnetically attracted to the materials included in cutting cone 102 and lug 101, respectively. Hence, the strength of the seal provided by seal assembly 105 b is determined in response to the magnetic attraction between magnetic rings 115 and 116 and cutting cone 102 and lug 101, respectively.

An advantage of seal assembly 105 b is that rigid ring 130 is “energized” into a dynamic sealing situation with cutting cone 102 by the magnetic attraction between magnetic ring 115 and cutting cone 102. Further, rigid ring 131 is “energized” into a dynamic sealing situation with lug 101 by the magnetic attraction between magnetic ring 116 and lug 101. In this embodiment, flexible ring 132 energizes rigid rings 130 and 131 into dynamic sealing situations with cutting cone 102 and lug 101, respectively, to a lesser extent, but this is mostly accomplished by magnetic rings 115 and 116. Hence, magnetic rings 115 and 116 affect how strongly dynamic sealing surfaces 112 a and 112 b engages cutting cone 102 and lug 101, respectively, and this determines how much material can flow through the interface between seal assembly 105 b and lug 101 and cutting cone 102.

Another advantage of seal assembly 105 b is that flexible ring 132 is spaced apart from dynamic sealing surfaces 112 a and 112 b by rigid rings 130 and 131, respectively, so it is less likely to become impregnated with debris. As mentioned above, when flexible ring 132 is impregnated with debris, it can cause the abrasion of the surfaces of lug 101 and cutting cone 102 that engage seal assembly 105 b.

Flexible ring 132 allows rigid rings 130 and 131 to move relative to each other to account for movement of lug 101 and cutting cone 102 relative to each other. Hence, the strength of the seal provided by seal assembly 105 b remains strong even as lug 101 and cutting cone 102 rotate.

It should be noted that, in this embodiment, seal assembly 105 b includes two magnetic rings, but it generally includes one or more magnetic rings. For example, in some embodiments, a magnetic ring is carried by rigid ring 130 and not by rigid ring 131. Further, in some embodiments, a magnetic ring is carried by rigid ring 131 and not rigid ring 130.

FIGS. 3 c and 3 d are side views of earth bit seal assembly 105 b in unflexed and flexed conditions, respectively. Earth bit seal assembly 105 b can be moved between the flexed and unflexed conditions in many different ways. One way seal assembly 105 b is moved between the flexed and unflexed conditions is in response to the movement between lug 101 and cutting cone 102. For example, cutting cone 102 can move in a radial direction, as indicated by direction arrow 127, and a non-radial direction, as indicated by direction arrow 128. Flexible ring 132 stretches in response to a force applied in direction 127 and bends in response to a force applied in direction 128.

Earth bit seal assembly 105 b moves between the flexed and unflexed conditions in response to the relative movement between cutting cone 102 and lug 101 for many different reasons. One reason is that flexible ring 132 extends between rigid rings 130 and 131 and rigid rings 130 and 130 are magnetically coupled with cutting cone 102 and lug 101, as discussed in more detail above. Further, flexible ring 132 and rigid rings 130 and 131 are coupled together. Hence, movement of cutting cone 102 relative to lug 101 stretches and compresses flexible ring 132.

Seal 105 b provides the same or similar advantages as seal assembly 105 a. For example, flexible ring 132 is spaced apart from dynamic sealing surface 112 a by magnetic ring 115 and rigid ring 130. Further, flexible ring 132 is also spaced apart from dynamic sealing surface 112 b by magnetic ring 116 and rigid ring 131. In this way, flexible ring 132 is less likely to become impregnated with debris, which can cause the abrasion of lug 101 and cone 102.

FIG. 4 a is a side view of an earth bit seal assembly 105 c in region 103, in accordance with the invention, which replaces seal assembly 105 of FIG. 1. Seal assembly 105 c forms dynamic sealing surfaces 112 a and 112 b with cutting cone 102 and lug 101, respectively. In this embodiment, seal assembly 105 c includes rigid rings 140 and 141 coupled together with a flexible ring 142, which extends between them. Flexible ring 142 allows rigid rings 140 and 141 to move relative to each other to account for relative movement between lug 101 and cutting cone 102. Hence, the strength of the seal provided by seal assembly 105 c remains strong even as lug 101 and cutting cone 102 rotate.

Flexible ring 142 covers an interface 143 between rigid rings 140 and 141, and restricts the flow of material between rigid rings 140 and 141. Flexible ring 142 and rigid rings 140 and 141 block debris from entering region 110 and keeps the lubricant in region 110 from flowing to region 109. In accordance with the invention, earth bit seal assembly 105 c is repeatably moveable between flexed and unflexed conditions, as will be discussed in more detail with FIGS. 4 c, 4 d and 4 e.

FIG. 4 b is an exploded perspective view of earth bit seal assembly 105 c. Flexible ring 142 can have many different configurations, but in this embodiment, flexible ring 142 is annular and includes an inwardly facing groove 145. A portion of flexible ring 142 on one side of groove 145 is engaged with rigid ring 140, and another portion of flexible ring 142 on the other side of groove 145 is engaged with rigid ring 141. In this way, flexible ring 142 extends between rigid rings 140 and 141 and covers interface 143 between rigid rings 140 and 141, as shown in FIG. 4 a.

Rigid rings 140 and 141 can have many different configurations, but in this embodiment, rigid ring 140 includes an upwardly facing groove 143 sized and shaped to receive magnetic ring 115. Further, rigid ring 141 includes a downwardly facing groove 144 sized and shaped to receive magnetic ring 116. Rigid ring 140 includes a downwardly facing groove 146 and rigid ring 141 includes an upwardly facing tongue 147, wherein groove 146 is sized and shaped to receive tongue 147.

As best seen in FIG. 4 a, magnetic ring 115 is carried by rigid ring 140 so that rigid ring 140 is magnetically coupled with cutting cone 102. Rigid ring 140 and magnetic ring 115 form dynamic sealing surface 112 a, which is engaged with cutting cone 102. Further, magnetic ring 116 is carried by rigid ring 141 so that rigid ring 141 is magnetically coupled with lug 101. Rigid ring 141 and magnetic ring 116 form dynamic sealing surface 112 b, which is engaged with lug 101.

Magnetic rings 115 and 116 are magnetically attracted to the materials included in cutting cone 102 and lug 101, respectively. Hence, the strength of the seal provided by seal assembly 105 c is determined in response to the magnetic attraction between magnetic rings 115 and 116 and cutting cone 102 and lug 101, respectively.

An advantage of seal assembly 105 c is that rigid ring 140 is “energized” into a dynamic sealing situation with cutting cone 102 by the magnetic attraction between magnetic ring 115 and cutting cone 102. Further, rigid ring 141 is “energized” into a dynamic sealing situation with lug 101 by the magnetic attraction between magnetic ring 116 and lug 101. In this embodiment, flexible ring 142 energizes rigid rings 140 and 141 into dynamic sealing situations with cutting cone 102 and lug 101, respectively, to a lesser extent, but this is mostly accomplished by magnetic rings 115 and 116. Hence, magnetic rings 115 and 116 affect how strongly dynamic sealing surfaces 112 a and 112 b engage cutting cone 102 and lug 101, respectively, and this determines how much material can flow through the interface between seal assembly 105 c and lug 101 and cutting cone 102.

Another advantage of seal assembly 105 c is that flexible ring 142 is spaced apart from dynamic sealing surfaces 112 a and 112 b, so it is less likely to become impregnated with debris. In this embodiment, flexible ring 142 is spaced apart from dynamic sealing surfaces 112 a and 112 b by rigid rings 140 and 141, respectively. When flexible ring 142 is impregnated with debris, it can cause the abrasion of the surfaces of lug 101 and cutting cone 102 that engage seal assembly 105 c.

It should be noted that seal assembly 105 c includes two magnetic rings in this embodiment, but it generally includes one or more magnetic rings. For example, in some embodiments, a magnetic ring is carried by rigid ring 140 and not by rigid ring 141. Further, in some embodiments, a magnetic ring is carried by rigid ring 141 and not rigid ring 140.

FIGS. 4 c and 4 d are side views of earth bit seal assembly 105 c in unflexed and flexed conditions, respectively. Earth bit seal assembly 105 c can be moved between the flexed and unflexed conditions in many different ways. One way seal assembly 105 c is moved between the flexed and unflexed conditions is in response to the movement between lug 101 and cutting cone 102. For example, cutting cone 102 can move in a radial direction, as indicated by direction arrow 127, and a non-radial direction, as indicated by direction arrow 128.

Earth bit seal assembly 105 c moves between the flexed and unflexed conditions in response to the relative movement between cutting cone 102 and lug 101 for many different reasons. One reason is that flexible ring 142 extends between rigid rings 140 and 141 and rigid rings 140 and 140 are magnetically coupled with cutting cone 102 and lug 101, as discussed in more detail above. Further, flexible ring 142 and rigid rings 140 and 141 are coupled together. Hence, movement of cutting cone 102 relative to lug 101 stretches and unstretches flexible ring 142.

Seal 105 c provides the same or similar advantages as seal assemblies 105 a and 105 b. For example, flexible ring 142 is spaced apart from dynamic sealing surface 112 a by magnetic ring 115 and rigid ring 140. Further, flexible ring 142 is also spaced apart from dynamic sealing surface 112 b by magnetic ring 116 and rigid ring 141. In this way, flexible ring 142 is less likely to become impregnated with debris, which can cause the abrasion of lug 101 and cutting cone 102.

FIG. 5 a is a perspective view of one embodiment of magnetic ring 115, which can be included with an earth bit seal assembly, such as those discussed herein. In this embodiment, magnetic rings 115 and 116 have the same shape and are annular. It should be noted, however, that magnetic ring 116 can have a different shape from magnetic ring 115. It should also be noted that rigid rings 120 and 121, as well as flexible ring 122, are also annular in shape.

FIG. 5 b is a bottom view of one embodiment of magnetic rings 115 and 116 attached to corresponding rigid rings 120 and 121. In this embodiment, magnetic rings 115,116 are carried by and attached to corresponding rigid rings 120 and 121. Magnetic rings 115 and 116 are positioned so they extend through the central periphery of corresponding rigid rings 120 and 121. However, it should be noted that magnetic ring 115 and 116 can be positioned closer to the inner and outer periphery of corresponding rigid rings 120 and 121. When a magnetic ring is positioned near the outer periphery of the corresponding rigid ring, the outer periphery of the rigid ring provides a stronger seal with the lug or cone and the inner periphery provides a weaker seal. Further, when the magnetic ring is positioned near the inner periphery of the corresponding rigid ring, the inner periphery of the rigid ring provides a stronger seal with the lug or cone and the outer periphery provides a weaker one.

One such example in which magnetic ring 115 or 116 is positioned near the inner periphery of corresponding rigid rings 120 and 121, is indicated by a substitution arrow 118 in FIG. 5 b. Another example, wherein magnetic ring 115 or 116 is positioned near the outer periphery of corresponding rigid rings 120 and 121, is indicated by a substitution arrow 119. In these embodiments, the rigid and magnetic rings are separate pieces attached together, but they can be formed as a single piece or multiple pieces in other examples.

FIG. 5 c is a bottom view of a magnetic ring 150, in accordance with the invention, which includes multiple pieces. In this embodiment, magnetic ring 150 includes a ring base 151 which carries a number of magnets 152. Magnets 115 e are attached to ring base 115 d and equidistantly spaced apart from each other. However, it should be noted that in some embodiments, magnets 152 do not have to be equidistantly spaced apart from each other. Magnets 152 and ring base 151 define dynamic sealing surface 112 a.

In accordance with the invention, the number of magnets 152 included with magnetic ring 150 determines the strength of the seal formed with the cone or lug. The strength of the seal increases as the number of magnets 152 increases. Further, the strength of the seal decreases as the number of magnets 152 decreases. Hence, a desired seal strength can be chosen by choosing the number of magnets included with magnetic ring 150.

FIG. 6 a is a flow diagram of a method 200 of providing a seal for an earth bit. In this embodiment, method 200 includes a step 201 of providing a flexible ring and a step 202 of coupling first and second rigid rings together using the flexible ring. In accordance with the invention, the flexible ring allows the first and second rigid rings to move relative to each other. The first and second rigid rings, as well as the flexible ring, form an earth bit seal assembly. Method 200 includes a step 203 of positioning the flexible ring and the first and second rigid rings to provide a seal between a lug and a cutting cone of an earth bit.

It should be noted that method 200 can include many other steps. For example, in some embodiments, method 200 includes a step of forming a dynamic seal between the first rigid ring and the lug and a static seal between the flexible ring and cutting cone. In some embodiments, method 200 includes a step of forming dynamic seals between the first and second rigid rings and the lug and cutting cone, respectively.

In some embodiments, method 200 includes a step of positioning the flexible ring so it does not engage the lug or cutting cone. In some embodiments, method 200 includes a step of moving the first and second rigid rings towards and away from each other by compressing and stretching, respectively, the flexible ring.

In some embodiments, method 200 includes a step of coupling a first magnetic ring to the first rigid ring, wherein the first magnetic ring couples the first rigid ring to the lug. In some embodiments, method 200 includes a step of coupling a second magnetic ring to the second rigid ring, wherein the second magnetic ring couples the second rigid ring to the cutting cone.

FIG. 6 b is a flow diagram of a method 210 of providing a seal for an earth bit. In this embodiment, method 210 includes a step 211 of providing a flexible ring and a step 212 of coupling first and second rigid rings together using the flexible ring. In accordance with the invention, the flexible ring allows the first and second rigid rings to move relative to each other. Method 210 includes a step 213 of positioning the flexible ring and the first and second rigid rings so they are carried by the lug. Method 210 includes a step 214 of rotatably mounting the cutting cone to the lug so that the earth bit seal assembly moves from the flexed to the unflexed condition in response.

FIG. 6 c is a flow diagram of a method 220 of manufacturing an earth bit seal assembly, in accordance with the invention. In this embodiment, method 220 includes a step 221 of providing a flexible ring and a step 222 of coupling first and second rigid rings together using the flexible ring. In accordance with the invention, the flexible ring allows the first and second rigid rings to move relative to each other.

It should be noted that methods 210 and 220 can include many other steps, several of which are discussed in more detail with method 200. Further, it should be noted that the steps in methods 200, 210 and 220 can be performed in many different orders.

While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims. 

1. An earth bit seal assembly, comprising: a flexible ring; and first and second rigid rings coupled together with the flexible ring, wherein the flexible ring allows the first and second rigid rings to move relative to each other.
 2. The assembly of claim 1, wherein the flexible ring allows the first and second rigid rings to move towards and away from each other.
 3. The assembly of claim 1, further including a first magnetic ring carried by the first rigid ring, wherein the flexible ring allows the first magnetic ring to move relative to the second rigid ring.
 4. The assembly of claim 3, wherein the flexible ring allows the first magnetic ring to move towards and away from the second rigid ring.
 5. The assembly of claim 3, further including a second magnetic ring carried by the first rigid ring, wherein the flexible ring allows the second magnetic ring to move relative to the first rigid ring.
 6. The assembly of claim 5, wherein the flexible ring allows the second magnetic ring to move towards and away from the first rigid ring.
 7. An earth bit, comprising: a lug and cutting cone rotatably coupled together; a flexible ring; and a seal assembly which includes first and second rigid rings coupled together with the flexible ring, wherein the seal assembly is repeatably moveable between flexed and unflexed conditions.
 8. The earth bit of claim 7, wherein the flexible ring is repeatably moveable between stretched and unstretched conditions.
 9. The earth bit of claim 7, wherein the flexible ring does not form a dynamic sealing surface with the lug or cutting cone.
 10. The earth bit of claim 7, wherein the flexible ring allows the first and second rigid rings to move relative to each other.
 11. The assembly of claim 7, wherein the flexible ring allows the first and second rigid rings to move towards and away from each other.
 12. The assembly of claim 7, further including a first magnetic ring which couples the first rigid ring to the lug, wherein the flexible ring allows the first magnetic ring to move relative to the second rigid ring.
 13. The assembly of claim 12, wherein the flexible ring allows the first magnetic ring to move towards and away from the second rigid ring.
 14. The assembly of claim 12, further including a second magnetic ring which couples the second rigid ring to the cutting cone, wherein the flexible ring allows the second magnetic ring to move relative to the first rigid ring.
 15. The assembly of claim 14, wherein the flexible ring allows the second magnetic ring to move towards and away from the first rigid ring.
 16. A method of providing a seal for an earth bit, comprising: providing a flexible ring; coupling first and second rigid rings together using the flexible ring, wherein the flexible ring allows the first and second rigid rings to move relative to each other; and positioning the flexible ring and the first and second rigid rings to provide a seal between a lug and a cutting cone.
 17. The method of claim 16, further including forming a dynamic seal between the first rigid ring and the lug and a static seal between the flexible ring and cutting cone.
 18. The method of claim 16, further including forming dynamic seals between the first and second rigid rings and the lug and cutting cone, respectively.
 19. The method of claim 16, further including positioning the flexible ring so it does not engage the lug or cutting cone.
 20. The method of claim 16, further including moving the first and second rigid rings towards and away from each other by compressing and stretching, respectively, the flexible ring.
 21. The method of claim 16, further including coupling a magnetic ring to the first rigid ring, wherein the magnetic ring couples the first rigid ring to the lug.
 22. The method of claim 16, further including coupling a magnetic ring to the second rigid ring, wherein the magnetic ring couples the second rigid ring to the cutting cone. 